Pearl-net trials. Data collected from fishing trials testing if plastic pearls reduce the amount of fish catches.

The mitigation trials took place onboard a Danish commercial set net vessel during three distinct periods, in November 2022, February 2023, and May-June 2023 in the Western Baltic Sea. All trials were conducted with a standard 3-folds trammel net used in this area to target Atlantic cod and flatfish. We used 18 identical net panels of approximately 60 m in horizontal length, of which 5 net panels were equipped with acrylic pearls on one of the outer net layers, resulting in 13 control and 5 treatment panels. The pearls were small acrylic glass spheres (Ø 8 mm) with a groove (4 mm long and 0.8 mm wide) into which to fit the net thread.Each fishing day during the course of the trial, the fisher set one string of nets consisting of 6 control nets, then 5 pearl nets, and lastly 7 control nets. As a result, control nets and pearl nets were always deployed on the same fishing grounds, at the same time, and soaked in the water for the same duration. The trials were recorded using electronic monitoring (EM). The EM system installed onboard (Black Box Video, Anchorlab, Denmark) consisted of a control unit, associated with a position sensor (GPS), and two waterproof CCTV (closed-circuit television) cameras.The data set is made on haul basis. For each haul the date, number of control-nets, number of pearl-nets, Kg of all fish catches and numbers of cod (Gadus Morhua) is registered. The catches of fish (in kg) was noted by the fisher carrying out the trials whereas the numbers of cod caught was registered from video analysis of all net hauls.

此次缓解试验于2022年11月、2023年2月以及2023年5月至6月，在波罗的海西部海域，于一艘丹麦商业拖网渔船上分三个不同的时段进行。所有试验均采用该地区用于捕捞大西洋鳕鱼和平鱼的标准化三重层刺网进行。试验中使用了18块约60米横向长度的相同网片，其中5块网片在其外层网的一侧配备了亚克力珍珠，形成13块对照组网片和5块处理组网片。这些珍珠为直径8毫米的小型亚克力玻璃球，球内有凹槽（长4毫米，宽0.8毫米），以便容纳网线。在试验过程中，每一天的捕鱼作业中，渔民都会设置一串网，包括6块对照组网、5块珍珠网以及最后7块对照组网。因此，对照组网和珍珠网总是在同一捕鱼区域、同一时间投放，并浸泡在水中相同的时间。试验通过电子监控（EM）进行记录。船上的电子监控系统（Black Box Video，Anchorlab，丹麦）由一个控制单元、一个位置传感器（GPS）以及两个防水闭路电视（CCTV）摄像头组成。数据集以拖网为单位制作。对于每一次拖网，记录了日期、对照组网数量、珍珠网数量、所有鱼类捕获的重量（千克）以及鳕鱼（Gadus Morhua）的数量。鱼类捕获的重量（千克）由执行试验的渔民记录，而捕获的鳕鱼数量则通过所有网次的视频分析进行登记。